In the Linux kernel, the following vulnerability has been resolved: wifi: mt7601u: fix an integer underflow Fix an integer underflow that leads to a null pointer dereference in 'mt7601u_rx_skb_from_seg()'. The variable 'dma_len' in the URB packet could be manipulated, which could trigger an integer underflow of 'seg_len' in 'mt7601u_rx_process_seg()'. This underflow subsequently causes the 'bad_frame' checks in 'mt7601u_rx_skb_from_seg()' to be bypassed, eventually leading to a dereference of the pointer 'p', which is a null pointer. Ensure that 'dma_len' is greater than 'min_seg_len'. Found by a modified version of syzkaller. KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 12 Comm: ksoftirqd/0 Tainted: G W O 5.14.0+ #139 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 RIP: 0010:skb_add_rx_frag+0x143/0x370 Code: e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 86 01 00 00 4c 8d 7d 08 44 89 68 08 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 cd 01 00 00 48 8b 45 08 a8 01 0f 85 3d 01 00 00 RSP: 0018:ffffc900000cfc90 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff888115520dc0 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffff8881118430c0 RDI: ffff8881118430f8 RBP: 0000000000000000 R08: 0000000000000e09 R09: 0000000000000010 R10: ffff888111843017 R11: ffffed1022308602 R12: 0000000000000000 R13: 0000000000000e09 R14: 0000000000000010 R15: 0000000000000008 FS: 0000000000000000(0000) GS:ffff88811a800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000004035af40 CR3: 00000001157f2000 CR4: 0000000000750ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: mt7601u_rx_tasklet+0xc73/0x1270 ? mt7601u_submit_rx_buf.isra.0+0x510/0x510 ? tasklet_action_common.isra.0+0x79/0x2f0 tasklet_action_common.isra.0+0x206/0x2f0 __do_softirq+0x1b5/0x880 ? tasklet_unlock+0x30/0x30 run_ksoftirqd+0x26/0x50 smpboot_thread_fn+0x34f/0x7d0 ? smpboot_register_percpu_thread+0x370/0x370 kthread+0x3a1/0x480 ? set_kthread_struct+0x120/0x120 ret_from_fork+0x1f/0x30 Modules linked in: 88XXau(O) 88x2bu(O) ---[ end trace 57f34f93b4da0f9b ]--- RIP: 0010:skb_add_rx_frag+0x143/0x370 Code: e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 86 01 00 00 4c 8d 7d 08 44 89 68 08 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 cd 01 00 00 48 8b 45 08 a8 01 0f 85 3d 01 00 00 RSP: 0018:ffffc900000cfc90 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff888115520dc0 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffff8881118430c0 RDI: ffff8881118430f8 RBP: 0000000000000000 R08: 0000000000000e09 R09: 0000000000000010 R10: ffff888111843017 R11: ffffed1022308602 R12: 0000000000000000 R13: 0000000000000e09 R14: 0000000000000010 R15: 0000000000000008 FS: 0000000000000000(0000) GS:ffff88811a800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000004035af40 CR3: 00000001157f2000 CR4: 0000000000750ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554
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